EFFECT OF DEPOSITION TIME ON STRUCTURAL AND OPTICAL PROPERTIES OF CdS THIN FILM PREPARED BY CHEMICAL BATH DEPOSITION METHOD IN ALKALINE MEDIUM

Abstract

Cadmium Sulfide thin films were prepared by chemical bath deposition (CBD) technique at bath temperature of 800C for various deposition time. The bath solution was a mixture of cadmium chloride and thiourea as source of Cd2+ and S2- respectively and ammonia hydroxide was used as complexing agent in basic medium. After deposition the film were annealed at temperature of 3000C for 90min. The effect of deposition time on the structural and optical properties of CdS thin film were investigated by XRD, FT-IR and Uv-Vis spectroscopy characterization technique. The XRD analysis revealed CdS thin film were cubic (Hawleyite) structure. The diffracted peaks are indexed (111),(200), (220) and (311) planes and with preferred orientation along the (111) plane. Estimated crystallite size and optical band gap was found in range of 11.7nm to 16.12nm and 1.8ev to 2.06ev respectively for deposition time 30min to 60min in 10min interval. The functional group of CdS thin films were proposed based on FTIR result obtained. The absorbance generally decreased with increase in wavelength and has relatively low values in the infrared region of the spectrum. A strong absorption was observed at wavelength range of 400 nm to 600 nm.